<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>bootstrap</title>
    <link rel="stylesheet" href="css/bootstrap.min.css">
    <style>
    .bg div{
        background: violet;
    }
    </style>
</head>
<body>
<div class="container">
    <div class="row">
        <div class="col-md-3 col-sm-6 col-xs-12">
            <img src="img/square-logo.png" alt="" class="img-responsive center-block">
        </div>
        <div class="col-md-3 col-sm-6 col-xs-12">
            <img src="img/google-logo.png" alt="" class="img-responsive center-block">
        </div>
        <div class="col-md-3 col-sm-6 col-xs-12">
            <img src="img/box-logo.png" alt="" class="img-responsive center-block">
        </div>
        <div class="col-md-3 col-sm-6 col-xs-12">
            <img src="img/intuit-logo.png" alt="" class="img-responsive center-block">
        </div>
    </div>
</div>
</body>
</html>